Powder flame spray gun nozzle



March 2, 1965 A. J. ROTOLICO 3,171,599

POWDER FLAME SPRAY GUN NOZZLE Filed March 5, 1963 AIR COMPRESSOR OXYGEN3 FUEL POWDER INVENTOR ANTHONY J ROTOL/CO 0 EYS United States PatentOffice 3,lll,5% Patented Mar. 2, 1965 3,171,599 POWDER FLAME SPRAY GUNNOZZLE Anthony J. Rotolico, Lynhrook, N.Y., assignor to Metco, Ind,Westbury, N.Y., a corporation of New Jersey Filed Mar. 5, 1963, Ser. No.262,987 2 Claims. (1. 29-85) This invention relates to a newconstruction of a nozzle for a powder flame spray gun.

Powder fiame spray guns are devices utilized for spraying heat-fusiblematerial, such as metal or ceramics which are fed to the gun in the formof a powder. As these guns are often used for spraying metal, they aresometimes commonly referred to as powder-type metal spray guns. Theseguns are often provided with burner jets for producing a conventionalcombustion flame and with means for conveying the powdered material tobe sprayed, generally entrained in a carrier gas, through the flame,where the powder is melted or at least heat softened, and thence awayfrom the gun, as for example onto a surface to be coated. United StatesPatent 2,961,335, of November 22, 1960, describes a powder-type flamespray gun. When operating the flame spray gun, as described in the saidpatent and other flame spray guns which were provided with a nozzleforming a combustion flame through which the powder was passed aphenomenon would sometimes occur which was known as nozzle loading. Thisphenomenon involved the sticking and solidification of the powder beingsprayed on the nozzle face which after a period of time would interferewith the efficient spraying operation and necessitate interruptionthereof and cleaning or even replacement of the nozzle.

This phenomenon would be more troublesome with the spraying of certainmaterials and when, for example, spraying powders which willexothermically react in the flame, the phenomenon is particularlyemphasized and troublesome. Furthermore, when spraying theseexothermically reacting powders, the same would become ignited in theflame causing a back-firing and interrupting the spraying operation.

One object of this invention is a new nozzle construction for a powdertype flame spray gun which has a substantially reduced tendency towardloading during spraying even when spraying materials, in connection withwhich this problem was particularly pronounced, and does not have theprior art back-firing tendencies even when spraying exothermicallyreacting powders.

These and still further objects will become apparent from the followingdescription read in conjunction with the drawing in which:

FIG. 1 is a vertical section of an embodiment of a nozzle in accordancewith the invention,

FIG. 2 is a front elevation of the nozzle shown in FIG. 1,

FIG. 3 is a vertical section of a further embodiment of a nozzle inaccordance with the invention,

FIG. 4 is a perspective view showing a still further embodiment of anozzle in accordance with the invention mounted on an extension head,and

FIG. 5 is a vertical section of the nozzle shown in FIG. 4 with theextension head being diagrammatically shown. ni

Referring to the embodiment shown in FIGS. 1 and 2 of the drawing, 1represents a nozzle body which is constructed of conventional material,as for example, leaded copper. The forward end of the nozzle body has asubstantially fiat nozzle face 2. Eight burner jets 3, arranged in theform of a ring, are drilled through the nozzle body and terminate at theface 2. The intermediate portion of the jets has a slightly enlargedbore at 4 and terminates at the rear face of the nozzle body in theannular groove 5. A central powder conduit 6 is drilled through thenozzle body and is concentrically positioned with respect to the ring ofburner jets 3. The forward end of the central powder conduit 6terminates as a cylindrical extension '7 which projects past the Hatportion 2. on the face of the nozzle body.

An annular channel 8 is cut into the face of the nozzle body and isconcentrically positioned between the central powder conduit 6 and ringof burner jets 3. The inner wall of the groove 8 is defined by thecylindrical extension 7.

A multiple number of air holes 9 radially extend through the side wallof the nozzle body in communication with the annular channel 8. In theembodiment shown eight such air holes are provided, one positionedbetween each pair of adjacent burner jets 3. The positioning of theseradial air holes may be seen by the dotted lines in FIG. 2.

In operation, the nozzle is attached to the forward end of a powder typeflame spray gun in the conventional manner, as for example by the use ofa nut which screws on the forward end of the gun and which engages theflange 10 provided on the nozzle body. The nozzle may thus be connectedto a gun of the type shown in United States Patent 2,961,335 inidentical manner as the nozzle shown on said gun. The fuel andcombustion supporting gas passages on the gun are in communication withthe groove 5 in the rear face of the nozzle body and a combustiblemixture of these gases, as for example acetylene and oxygen, passes fromthe groove 5 through the portion 4 of the burner jets and out throughthe burner jets 3 where the same is ignited forming a ring or sheath offlame surrounding the central powder conduit 6. The central powderconduit 6 is in communication with the means provided in the flame spraygun for feeding powder entrained in a carrier gas and the entrainedpowder passes through the conduit 6 out of the nozzle and within theflame sheath propagated from the ring of burner jets 3. The powderparticles are melted or at least softened and propelled away from thegun, as for example onto a surface being coated. The action of thecombustible gases passing through the burner jets 3 for combustion, andto a lesser extent, the passage of the entrained powder through thecentral powder conduit 6 aspirates ambient air into the air holes 9 andthrough the channel 3 around the cylindrical extension 7 forming aninitial protective or buffer sheath of syphoned air between the powderas it leaves the central powder conduit 6 and the flame sheath.

In all respects the flame spray gun is operated in the conventionalmanner, as for example in the manner de scribed in United States Patent2,961,335 and the nozzle is simply used in place of the nozzle shown insaid patent.

With the use of the nozzle in accordance with the invention, however,the tendency toward loading with melted powder is substantiallydecreased even when spraying materials which normally have a pronouncedtendency toward such nozzle loading, as for example, exothermically reacting powder, and the tendency toward back-firing is substantiallyreduced.

The embodiment shown in FIG. 3 is identical to that shown in FIGS 1 and2 in construction and operation except that the cylindrical extension 7is enclosed at its forward end at 11 and provided with a multiple numberof jets 12, as for example eight jets equally spaced on a circle andwhich are divergent, i.e. directed outwardly from the axis of theconduit 6.

This embodiment is particularly adaptable for spraying ceramic and otherhigh melting point material powders on passing through the central outerconduit 6 are V 3 diffused outwardly by the divergent direction of thejects 12 into the flame sheath.

The nozzle, as shown in FIGS. 421ml 5, is for use with a conventionalextension head, as for example for spraying the inside of cylinders. Inthis embodiment the nozzle body is formed of three parts, i.e. the outerbody 13, the intermediate cylindrical insert 14, and the innercylindrical insert 15, which are all constructed of copper and may beassembled as an integral unit, as for'example with the soldered joints16 and 17. The intermediate cylindrical insert 14 has a multiple numberof burner jets 19 which are arranged in the form of a ring and terminateat the flat nozzle face 18. The burner jets are in communication withthe annular channel 211 formed between the outer body 13 andintermediate insert 14. A passage 21 in the outer body of 13communicates the groove with a cylindrical socket bore 2 2 for theoxygen and fuel gas conduit 23 provided in the extension head 24. Acentral powder conduit 25 is provided in the inner insert 15 and nozzlebody 13 and is concentrically positioned within the ring of burner jets19. The central insert 15 form a cylindrical extension 26 of the centralpowder conduit 25 which extends past the fiat portion 18 of the nozzleface. A passage 27 in the body 13 communicates the powder conduit 25with a cylindrical socket 28 into which the powder conduit 29 of theextension head fits. An annular channel 30/ is formed by the centralinsert 15 between it and the intermediate 14. This annular channel 31)is concentrically positioned between the central powder conduit 25 andthe ring of burner jets 19. An annular groove 31 is provided in the body13 and 7 this groove is in communication with the channel 30 by means ofone or more passages 32 in the intermediate insert 14 A passage 33 inthe body 13 communicates the groove 31 with the rear face of the nozzlebody and a compressed air conduit 34 leadsthrough the extension head toan air metering jet 35, and thence to the passage 33. Air is fed throughthe air conduit 34 by meansof the air compressor diagrammatically shown.The nozzle body is held in place on the extension head by means of thethreaded nut 36. V

V In operation, fuel and combustion supporting gases, as for exampleoxygen, acetylene, or the like, pass through the conduit 23 and thepassage 21 into the grooveZQ and thence through the burner jets 19 wherethe same is ignited at the nozzle face. forming a ring or sheath of theflame. The powder is to be sprayed, entrained in the carrier gas, ispassed through the conduit 29, the passage 27 and out through thecentral powder conduit 25 whence 'the same passes through the flame andis melted or at least heat softened and propelled against the surface tobe coated. Compressed air from the air compressor is passed through theconduit 34, passes through the meter ing jet 35, passage 33, into thegroove 31. From the groove 31, the air passes through the passage 32into the annular channel 30 and out of the same as a buffer sheath ofair between the entrained powder emerging from the central powderconduit 25 and the flame sheath formed from the ring of burner jets 19.

The spraying in all respects is effected in the conventional manner, andthe extension may, for example, be positioned in a cylinder to spray theside wall thereof. With the construction, nozzle loading and back-firingtendencies are substantially surpressed.

The provision of the cylindrical extension of the central powder conduitpassage and the annular channel surrounding the same through which airpasses apparently sets up flow characteristics which prevent theconventionally occurring nozzle loading and back-firing tendencies. Thecylindrical extension should extend past the nozzle face at least A ofan inch and in connection with conventiontional nozzle sizes, having forexample a central powder conduit with a diameter between and ispreferably extended from t'o' about past the nozzle face.

In the embodiment in which the air passing through the annular channelsurrounding the powder conduit is forced from a compressed air source,as contrasted to being aspirated, the extension may be dispensed withand the powder conduit may terminate flush with the nozzle face. In thisembodiment, however, the air should be passed through the device at aflow rate of at least 0.3 s.c.f.m. and preferably from 0.5 s.c.f.m. to 1s.c.f.m.

While the invention has been described in detail with reference tocertain specific embodiments, various changes and modifications whichfall within the spirit of the invention and scope of the appended claimswill become apparent to the skilled artisan. The invention, therefore,is only intended to be limited by the appended claims or theirequivalents wherein I have endeavored to claim all inherent novelty.

I claim:

1. A nozzle for a powder flame spray gun comprising a nozzle bodyterminating with a nozzle face having a substantially flat portion, amultiple number of burner jets arranged in the form of a ring in saidbody and terminating at the flat portion of said face, a central powderconduit extending through said body concentrically positioned Withinsaid ring of burner jets and terminating as a cylindrical extension pastsaid fiat portion of said face, an annular channel in said face,concentrically positioned between said central powder con duit and saidring of burner jets surrounding said cylindrical extension and amultiple number of air holes References Cited in the file of this patentUNITED STATES PATENTS 2,209,323 Corley July 30, 1940 2,643,955 Powers etal. June 30, 1953 2,890,419 Kough' July 23, 1957 V FOREIGN PATENTS1,054,610 France Oct. 7, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,171,599 March 2, 1965 Anthony J. Rotolico It ishereby certified that error appears in the above numbered patentreq'iiring correction and that the said Letters Patent should read ascorrected below Column 2, lines 71 and 72, after "powders" insert inthat the entrained powders column 3, line 21, for "form" read forms line47, strike out "is"; column 4, line 12, for "conventiontional" readconventional Signed and sealed this 3rd day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER I EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A NOZZLE FOR A POWDER FLAME SPRAY GUN COMPRISING A NOZZLE BODYTERMINATING WITH A NOZZLE FACE HAVING A SUBSTANTIALLY FLAT PORTION, AMULTIPLE NUMBER OF BURNER JETS ARRANGED IN THE FORM OF A RING IN SAIDBODY AND TERMINATING AT THE FLAT PORTION OF SAID FACE, A CENTRAL POWDERCONDUIT EXTENDING THROUGH SAID BODY CONCENTRICALLY POSITIONED WITHINSAID RING OF BURNER JETS AND TERMINATING AS A CYLINDRICAL EXTENSION PASTAND SAID FLAT PORTION OF SAID FACE, AN ANNULAR CHANNEL IN SAID FACE,CONCENTRICALLY POSITIONED BETWEEN SAID CENTRAL POWDER CONDUIT AND SAIDRING OF BURNER JETS SURROUNDING SAID CYLINDRICAL EXTENSION AND AMULTIPLE NUMBER OF AIR HOLES RADIALLY EXTENDING THROUGH THE SIDE WALL OFSAID NOZZLE BODY IN COMMUNICATION WITH THE AMBIENT ATMOSPHERE AT ONE ENDAND IN COMMUNICATION WITH SAID ANNULAR CHANNEL AT THE OTHER END.